JP2000239658A - Liquid coolant composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid coolant composition not only capable of inhibiting or preventing discoloration of an aluminum material but also excellent in rust proof properties. SOLUTION: This composition comprises a freezing point depressant containing as an effective component at least either one of alcohols and glycols, a rust proof agent and further a barium compound. The ratio of the barium compound is 0.0001-0.05 wt.% in terms of the barium element. The rust proof agent is at least one selected among silicates, phosphates, molybdates, nitrates, tungstates, aromatic monobasic and polybasic carboxylates, aliphatic monobasic and polybasic carboxylates, triazole compounds and thiazole compounds. Further is preferably incorporated at least one selected from sequestering agents comprising a carboxylic acid or a salt thereof to an amino nitrogen, polyphosphoric acids and polycarboxylic acid type polymers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coolant composition for use as a coolant for an internal combustion engine such as an automobile or a ship, or as a brine for an industrial plant, and more particularly, to a method for preventing discoloration of the surface of an aluminum alloy. And a coolant composition exhibiting an excellent rust-preventing effect.

[0002]

2. Description of the Related Art Conventionally, coolant compositions mainly used for internal combustion engines such as automobiles and marine vessels include metal materials such as aluminum alloy, steel, cast iron, brass, solder, and copper which constitute the internal combustion engine. In addition, various rust inhibitors having an effect of preventing corrosion are added. Representative rust inhibitors include phosphates, borates, silicates, nitrates, nitrites, benzoates, triazole compounds, thiazole compounds, alkanolamine salts and the like.

[0003] In recent years, aluminum materials such as aluminum alloys have been frequently used as metals constituting internal combustion engines such as automobile engines as the weight thereof has been reduced. The demand for things is growing.

Alkanolamine as a rust preventive suitable for aluminum materials has a problem of producing nitrosamine which is a carcinogen during use together with nitrites. Therefore, a cooling liquid composition containing no alkanolamine ( Non-amine type cooling liquid compositions) are required.

[0005]

However, the non-amine type coolant composition has a problem in that the surface of the aluminum material is discolored, and when the discoloration is remarkable, blackening occurs.

Accordingly, an object of the present invention is to suppress or prevent discoloration of a metal material, particularly an aluminum material,
Another object of the present invention is to provide a coolant composition having excellent rust prevention properties.

[0007]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that by using a barium compound as a component of a non-amine type coolant composition, discoloration of an aluminum material can be prevented and corrosion can be prevented. It has been found that the present invention is prevented, and the present invention has been completed.

That is, the present invention is a cooling liquid composition containing a freezing point depressant containing at least one of alcohols and glycols as active ingredients, a rust preventive, and further containing a barium compound.

In the non-amine type coolant composition of the present invention, the barium compound is used, so that an excellent sealing effect of the barium compound on the aluminum material is exerted. While preventing the corrosion, the corrosion of the aluminum material can be suppressed or prevented.

On the other hand, the same periodic table II as the barium compound
Discoloration and corrosion of the aluminum material can be suppressed by using a magnesium compound or a calcium compound of group A, but the effect of preventing discoloration and corrosion is smaller than that of the barium compound. Has excellent discoloration and corrosion effects. This is because the aluminum material has a state in which the spacing between atoms is large in the crystal structure and microscopic holes are formed, and the barium atoms of the barium compound block the microscopic holes of the aluminum material. This is probably because the sealing effect is excellent.

The cooling liquid composition is usually used after being diluted to a suitable concentration with water. In this case, in the cooling liquid composition containing a magnesium compound or a calcium compound, the magnesium compound contained in the water is not used. , Calcium compounds and / or their ions (magnesium ions, calcium ions) are contaminated, making it impossible to control the concentration of magnesium compounds or calcium compounds during use. Furthermore, since the hardness of water varies from region to region and from country to country, it is extremely difficult to substantially control the concentrations of magnesium and calcium compounds. In particular, since the amounts of the magnesium compound and the calcium compound used are extremely small, it is not practical to be unable to control these amounts.

However, the non-amine type coolant composition of the present invention not only has an excellent effect of preventing discoloration and corrosion of an aluminum material, but also can be used after dilution with water.
It is possible to control the concentration of the barium compound that is used in a small amount.

In the coolant composition of the present invention, the ratio of the barium compound is preferably 0.0001 to 0.05% by weight in terms of barium element with respect to the total amount of the coolant composition.

Examples of the rust preventive include silicate, phosphate, molybdate, nitrate, tungstate, aromatic monovalent or polyvalent carboxylate, aliphatic monovalent or polyvalent carboxylate, and triazole. At least one selected from a compound and a thiazole compound can be suitably used.

In a preferred embodiment of the coolant composition of the present invention,
Further, it contains a sequestering agent which is a compound in which a carboxylic acid or a salt thereof is bonded to an amino nitrogen. When such a sequestering agent is contained, an excellent effect of suppressing or preventing discoloration and corrosion of aluminum can be further exhibited.

In a preferred embodiment of the coolant composition of the present invention, the composition further contains at least one selected from polyphosphoric acid and polycarboxylic acid type polymers. When a polyphosphoric acid and / or polycarboxylic acid type polymer is used in combination, discoloration of aluminum can be suppressed or prevented, and rust prevention can be further improved.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION (Barium compound) The barium compound is not particularly restricted but includes, for example, barium oxide (barium oxide), barium hydroxide (barium hydroxide), barium halide and inorganic compound. Barium salts of acids, barium salts of organic acids and the like can be mentioned. More specifically, the halide of barium includes, for example, chloride (barium chloride), iodide (barium iodide), and the like.

Barium salts of inorganic acids include, for example, permanganate (barium permanganate), chromate (barium chromate), carbonate (barium carbonate), nitrate (barium nitrate), sulfate (sulfate) Barium), titanate,
Tungstate (barium tungstate), borate, phosphate (barium phosphate), dihydrogen phosphate (barium dihydrogen phosphate) and the like are included.

Examples of barium salts of organic acids include, for example, formate (barium formate), acetate (barium acetate), propionate (barium propionate), butyrate (barium butyrate), and valerate (barium valerate). ), Laurate (barium laurate), stearate (barium stearate), oleate (barium oleate),
Barium salts of aliphatic monovalent carboxylic acids which may have a substituent such as glutamate (barium glutamate), lactate (barium lactate), citrate (barium citrate); oxalate, malonate , Succinate, maleate, fumarate, sebacate, malate, tartrate and the like, optionally substituted barium salts of aliphatic polycarboxylic acids; benzoate, phthalic acid Examples thereof include barium salts of aromatic monovalent or polyvalent carboxylic acids which may have a substituent, such as salts, terephthalates, salicylates, and mandelic salts.

The organic acid barium salts include barium ethylenediaminetetraacetate, barium ethylenediaminetetraacetate, barium diethylenetriaminepentaacetate, barium nitrilotriacetate, barium hydroxyethylethylenediaminetriacetate, barium dihydroxyethylethylenediaminediacetate. Salt, 1,
Barium 3-propanediaminetetraacetate, barium diethylenetriaminepentaacetate, barium triethylenetetramine hexaacetate, barium hydroxyethyliminodiacetate and the like can also be used.

The barium compound is preferably a water-soluble barium compound. Preferred barium compounds include barium hydroxide, barium nitrate, barium sulfate, barium ethylenediaminetetraacetate.

The amount of the barium compound used is not particularly limited. For example, the total amount of the cooling liquid composition is converted to barium element, that is, the barium element concentration is set to 0.1.
0001-0.05% by weight, preferably 0.0005-0.05
0.03% by weight. If the proportion of the barium compound is less than 0.0001% by weight in terms of barium element, the discoloration prevention and rust-prevention effects decrease, while the discoloration prevention and rust-prevention effects are reduced even if added in excess of 0.05% by weight. This is because there is not much improvement and there is no cost merit.

(Freezing Point Depressant) The freezing point depressant contains at least one of alcohols and glycols as an active ingredient. The alcohols and glycols are not particularly limited, and for example, methyl alcohol, ethyl alcohol, isopropyl alcohol, monoethylene glycol, propylene glycol, glycerin and the like are preferably used. The freezing point depressants can be used alone or in combination of two or more. As the freezing point depressant, alcohols and / or glycols can be used in combination with other components of the freezing point depressant, but preferably only alcohols and / or glycols are used.

The amount of the freezing point depressant to be used is not particularly limited, and can be appropriately selected according to the type and purpose of use.

(Rust Inhibitor) As the rust inhibitor, a non-alkanolamine salt-based rust inhibitor is used. As a rust inhibitor,
As long as it is a non-alkanolamine salt-based rust preventive, it is not limited to an inorganic rust preventive and an organic rust preventive, and various conventionally known ones can be used. Such non-alkanolamine salt-based rust inhibitors include silicates, phosphates,
Molybdate, nitrate, tungstate, aromatic 1
At least one rust preventive selected from a monovalent or polyvalent carboxylate, an aliphatic monovalent or polyvalent carboxylate, a triazole compound, and a thiazole compound is preferable. When the rust preventive is in the form of a salt, the type of the salt is not particularly limited, but is preferably an inorganic salt such as a sodium salt. The rust inhibitors can be used alone or in combination of two or more.

The amount of the rust inhibitor used is not particularly limited, and is, for example, about 0.1 to 30% by weight, preferably about 0.5 to 15% by weight, based on the total amount of the cooling liquid composition.

(Sequestering Agent) The sequestering agent is not particularly limited as long as it is a compound in which a carboxylic acid or a carboxylate is bonded to an amino nitrogen. Examples of such sequestering agents include ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), nitrilotriacetic acid (NTA), hydroxyethylethylenediaminetriacetic acid (HEDTA),
Dihydroxyethylethylenediamine diacetic acid (DHED
DA), 1,3-propanediaminetetraacetic acid (1,3
-PDTA), diethylenetriaminepentaacetic acid (DT
PA), triethylenetetramine hexaacetic acid (TTH
A), hydroxyethyliminodiacetic acid (HIMDA)
And their salts (eg, sodium salt, potassium salt,
Barium salts, calcium salts, magnesium salts, manganese salts, zinc salts, cobalt salts, and mixed salts thereof). The sequestering agents can be used alone or in combination of two or more.

When the sequestering agent has a barium salt structure, it can be used also as the barium compound.

The amount of the sequestering agent to be used is not particularly limited.
It is about 10% by weight, preferably about 0.01 to 1.0% by weight.

(Polyphosphoric acid and polycarboxylic acid type polymer) The polyphosphoric acid is not particularly limited. For example, pyrophosphoric acid, tripolyphosphoric acid, 1-hydroxyethane-
Examples thereof include 1,1-diphosphonic acid, aminotrimethylenephosphonic acid, ethylenediaminetetramethylenephosphonic acid, and phytic acid. The polycarboxylic acid type polymer is a polymer having a plurality of carboxyl groups, for example, polyacrylic acid, maleic acid / acrylic acid copolymer and the like. The polyphosphoric acid and polycarboxylic acid type polymers can be used alone or in combination of two or more.

The amount of the polyphosphoric acid and / or polycarboxylic acid type polymer is not particularly limited, and is, for example, 0.001 to 10% by weight, preferably 0.01 to 1.0% by weight based on the total amount of the cooling liquid composition. % By weight.

In the coolant composition of the present invention, the barium compound is a compound containing a barium element and a group IIA metal which is the same in the periodic table of the element, that is, a group IIA metal compound (magnesium compound, calcium compound) other than the barium compound. Compounds, strontium compounds, etc.).

The non-amine type coolant composition of the present invention suppresses or prevents discoloration of the aluminum material and has an excellent rust-preventing effect. Useful as a coolant composition for use as brine.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. Examples 1 to 9 and Comparative Examples 1 to 5 Non-amine type cooling liquid compositions were prepared by mixing and dissolving the compositions shown in Tables 1 and 2, respectively. In Tables 1 and 2, the unit of the mixing ratio of each composition is% by weight based on the total amount of the composition. The pH of the test liquid of the cooling liquid composition was adjusted to pH = 7.7 using phosphoric acid or potassium hydroxide.

[0035]

[Table 1]

[0036]

[Table 2]

The following materials were used as raw materials. (Barium compound)-Barium nitrate (Table 1 or Table 2 also shows the barium nitrate ratio (barium element concentration) when barium nitrate is converted to barium element)-Barium hydroxide (table 1, the ratio of barium hydroxide converted to barium element (barium element concentration) is shown together with the ratio of barium hydroxide. (Polyphosphoric acid and polycarboxylic acid type polymer) 1-hydroxyethane- 1,1-diphosphonic acid (Table 1
Or, in Table 2, it is abbreviated as “HEDPA”) Acrylic acid-maleic acid copolymer (weight average molecular weight: 6,000) (In Table 1 or Table 2, it is abbreviated as “Ac-Ml copolymer”) (Sequestration of metal ions) Agent) ・ Sodium salt of ethylenediaminetetraacetic acid (abbreviated as “EDTA-Na salt” in Table 1 or Table 2) ・ Sodium salt of nitrilotriacetic acid (abbreviated as “NTA-Na salt” in Table 1 or Table 2) (Rust inhibitor) ・ Disodium phosphate ・ Sodium benzoate ・ Sodium salt of 2-mercaptobenzothiazole (abbreviated as “MB-Na salt” in Table 1 or Table 2) ・ Benzotriazole ・ Sodium nitrate ・ Molybdenum Sodium acid (freezing point depressant) ・ Monoethylene glycol (others) ・ Water ・ Calcium nitrate (In Table 2, calcium nitrate The ratio (calcium element concentration) when the calcium nitrate is converted to the calcium element is also shown together with the ratio of the magnesium nitrate (in Table 2, the magnesium nitrate was converted to the magnesium element together with the magnesium nitrate ratio in Table 2). The percentage at the time (magnesium element concentration) is also shown)

(Evaluation) The cooling liquid compositions obtained in Examples 1 to 9 and Comparative Examples 1 to 6 were subjected to JIS K-2234.
A corrosion test was performed based on an antifreeze (aluminum casting heat transfer surface corrosion test), the amount of corrosion was measured, and the appearance change before and after the test was examined. The results are also shown in Table 1 or Table 2. The “corrosion amount” is a value (unit: mg / cm ² ) obtained by subtracting the mass of the test piece before the test from the mass of the test piece after the test and dividing the difference by the area of the contact portion between the test piece and the test solution. Point to. The evaluation criteria of “change in appearance” are shown in the order of no discoloration> slight discoloration> dark gray> black discoloration. The test conditions are as follows. (Test conditions), cooling solution concentration: 25 vol%, the test piece: JIS H-5202 prescribed in the aluminum alloy casting AC2B-F-test temperature: 135 ° C., test time: 168 hours, the test solution Cl ^- amount: 100 ppm・ Pressure pressure: 180 kPa

As shown in Tables 1 and 2, since the cooling liquid composition according to Example 1 contains a barium compound (barium nitrate), the discoloration of the aluminum alloy is suppressed and almost no discoloration occurs. Also, the amount of corrosion is suppressed.

Example 2 using a barium compound and a polyphosphoric acid or polycarboxylic acid type polymer
In the cooling liquid compositions according to Nos. 1 to 3, discoloration of the aluminum alloy is prevented, and no discoloration occurs. Further, the amount of corrosion is significantly reduced, and the rust prevention effect is excellent.

Further, in the cooling liquid compositions according to Examples 4 and 5, in which a barium compound and a sequestering agent, which is a compound in which a carboxylic acid or a carboxylate is bonded to an amino nitrogen, are used. Discoloration of the aluminum alloy is prevented and rust prevention is excellent.

The amount of the barium compound used was 0.0001% by weight in terms of the barium element, and the amount of corrosion was reduced in the coolant composition according to Example 6 as compared with Comparative Example 1. The degree of discoloration is also dark gray, and discoloration and corrosion of the aluminum material are suppressed.

In the cooling liquid composition according to Example 7, in which the amount of the barium compound used is 0.05% by weight in terms of barium element, discoloration of the aluminum material is prevented and corrosion is hardly caused.

The cooling according to Example 8 using a barium compound, a polyphosphoric acid or polycarboxylic acid type polymer, and a sequestering agent which is a compound in which a carboxylic acid or a carboxylate is bonded to an amino nitrogen. In the liquid composition, discoloration of the aluminum alloy is further prevented, and corrosion is also prevented.

In the coolant composition according to Example 9 using barium hydroxide as the barium compound, the discoloration of the aluminum alloy was suppressed and the corrosion was also suppressed.

In the cooling liquid compositions according to Comparative Examples 1 and 2 containing no barium compound, the aluminum alloy was discolored and turned black. Also, the amount of corrosion is large.

In Comparative Example 3, the amount of the barium compound used was 0.00005% by weight as the barium element concentration. Although the amount of corrosion was smaller than that of Comparative Example 1, the discoloration of the aluminum alloy was reduced. It has been turned black.

In Comparative Example 4, the amount of the barium compound used was 0.10% by weight as the barium element concentration, and the amount of corrosion was extremely small and almost no discoloration occurred.
Compared with the embodiment, the effect of increasing the used amount is not so large, and the cost merit is small.

Further, Comparative Example 5 or Comparative Example 6 was a case where calcium nitrate or magnesium nitrate was used. The corrosion amount was reduced as compared with Comparative Example 1, and the discoloration of the aluminum compound was suppressed. The effect of preventing corrosion and the effect of preventing discoloration of the aluminum alloy are smaller than when a compound is used (Example 1 and the like). That is,
When a barium compound and a calcium compound or a magnesium compound having the same metal element concentration are used, a barium compound has an excellent rust-preventing effect and can largely prevent discoloration of an aluminum material. this is,
This is probably because the barium compound has an excellent sealing action or effect of closing the microscopic pores of the aluminum material.

[0050]

The cooling liquid composition of the present invention, which contains a barium compound, can suppress or prevent discoloration of the aluminum material and exhibit excellent rust prevention. When a specific metal ion sequestering agent or a polyphosphoric acid and / or polycarboxylic acid type polymer is used together with the barium compound, discoloration of the aluminum material can be further prevented and rust prevention can be enhanced.

Claims (5)

[Claims] 1. A cooling liquid composition containing a freezing point depressant containing at least one of alcohols and glycols as an active ingredient, a rust preventive, and further containing a barium compound. 2. The ratio of the barium compound is 0.0001 to 0.0001 in terms of barium element with respect to the total amount of the coolant composition.
The cooling liquid composition according to claim 1, which is 0.05% by weight. 3. The rust inhibitor comprises a silicate, a phosphate, a molybdate, a nitrate, a tungstate, an aromatic monovalent or polyvalent carboxylate, an aliphatic monovalent or polyvalent carboxylate,
3. The coolant composition according to claim 1, wherein the coolant composition is at least one selected from a triazole compound and a thiazole compound. 4. The cooling liquid composition according to claim 1, further comprising a sequestering agent, wherein the carboxylic acid or a salt thereof is a compound bonded to an amino nitrogen. 5. The coolant composition according to claim 1, further comprising at least one selected from a polyphosphoric acid and a polycarboxylic acid type polymer.